Door



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DOOR

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INVENTOR. Raw 4. Dw-a-w BY Arro aways y 1960 R. 1.. DUGGER 2,937,415

DOOR

Filed Sept. 7. 1954 8 Sheets-Sheet 8 FIE. E1

INVENTOR. R00 4. D0665)? 4rro avers United States Patent noon Ral h L. Dugger, Box 260A, Rte. 1, Hopkins, Minn.

Filed Sept. 7, 1954, Ser. No. 454,365

Claims. (Cl. -16) "ice some stabilizing device at the bottom to preventltheir flapping in the wind. Usually stakes, guide shoes or guide rollers are provided at the base but these, being exposed to the weather and subject to the difiiculty that the door may warp, must be set loosely so as to allow the door to be moved and this circumstance accordingly makes it impossible to fabricate such a door to remain actually tight during its useful life. Rolling doors which are composed of panels hinged together and mounted on curve track so as to roll back into and against a side wall of the building, such as a hangar, will take up space within the building against the side wall. This valuable space is frequently along the sides of the building and is fairly sizeable, particularly where the flat individual door panels must turn to follow the curve of a curved track leading into the building interior. In airplane hangars, particularly, the width dimension of the buildagricultural machinery and industrial buildings such as doors for warehouses, service garages, highway garages and the like. In many instances, no provision is made for the heating of the building and it is only desired that the door protect the equipment from sun, wind, rain and snow and provide a dry building space in which the equipment may be satisfactorily stored.

The requirements of ease and rapidity of operation vary. For military aircraft hangers, it is desired that the door be capable of being opened with great rapidity,.

particularly where the storage of fighter aircraft is involved. For other aircraft such as the storage of commercial and civilian aircraft, rapidity of operation is not always a prime requisitebut ease of operation is always desired. In the storage of many private aircraft, the :aircraft owner may desire to open and close the doors .single handedly without assistance from others. Hand power operation is desirable from the standpoints of reduced cost and lesser complexity and the door should be capable of operation without undue effort and at a reasonably rapid rate. The building arts have heretofore provided many types of doors for the aforesaid purposes but all have been subject to varying objections. The most common and least expensive type of door used for airplane hangars, industrial and agricultural buildings, :and the like is the ordinary rolling door hung from an overhead track. Where the spans are large, as in airgplane hangars and other space restrictions are imposed, the door Width is separated into several segmentsor panels. Thus a door of 40 foot span may be divided .into four overlapping panels of slightly more than 10 'feet and each arranged to roll on a separate overhead :track while hanging vertically so as thus to be movable iinto an out-of-the-way position. Other doors are provided which are maintainedin a vertical plane but the panels are hinged together on vertical hinge lines and athe track is curved so that the door may bend as it is .rolled out of the way along an inner side wall of the :building.

All doors which remain in a vertical position during opening and closing movement, such'as the ordinary rolling door on a straight or curved track, are subject to several difiiculties. The chief objection to such vertical doors is that they do not aiford' adequate protection. The panels which may be fabricated of wood or metal or metal sheeting on a wood or metal frame, are usually ;subject to some warping and while the door is intended blow. Furthermore, such doors must be provided with ing interior is a critical dimension because the wing tips of the airplane frequently are not very far from the side edges of the door opening and the sidewalls of the building. Therefore, if some of the width of the door span is consumed by the thickness of the door and clearance requisite to the satisfactory operation of the door, then that much of the useful span of the door and of the building interior is lost from the service for which it was intended.

The second principal objection to the vertical rolling door is the necessity for keeping a space clear for the lower edge of the door as it moves. In snow, this can be a real problem, particularly if wet snow freezes in place. Even a little ice or hard snow under the lower edge of the door will make movement of the door very diflicult.

There are several patterns of overhead doors that have been used for'large building openings such as hangars. One of these, commonly called the jack-knife door utilizes a door composed of two panels divided along a horizontal line about midway from top to bottom of the door with the upper and lower panels hinged together. The lower edge of the door is heavily reinforced and is guided by vertical guides along the side edges of the door opening and provision is made for vertically elevating the heavy reinforcement at the bottom of the door and hence lifting the door into a somewhat folded condition as it is opened with the hinge line projected out from the building. "Such doors are subject to several difficulties, the chief of which is that a very heavy construction must be provided for the door itself which is held in a hinged condition exteriorly of the building when it is opened. The heavy construction consequently necessitates heavy gear for elevating the door and heavy guide rails along the vertical side edges of the door opening. Such heavy structures consume part of the useful span of the door, and the heavy operating gear requires an extended time of operation (or power equipment) for opening and closing the door.

Variations of the foregoing door types-are many but all are subject to objection along one or more lines.

It is an object of the present invention to provide a door for large widespan door openings capable of being manufactured at relatively low cost and rigged so that it can be operated easily and quickly even by hand operation.

It is a further object to provide an improved 'door construction in which large sizes of doors are capable of being operated by a few easy turns of the crank by one person or utilizing only low horsepower motor equipment for actuating the door. Itis another object of the invention to provide a widespan door of unitary construction including mountings and riggings for elevating the door upwards and backwards into the building to a position in which all except a minimal portion of the door is within the building structure and protected from the elements when the door is open. It is another object of the invention to provide an improved door for large widespan openings composed of a single unitary panel extending from one side edge to the other side edge of the door opening and so rigged that, when the door is elevated the entire span of the opening is useable, the opening being (if desired) devoid of jambs or other clearance consuming protuberances. It is a further object of the invention to provide subcombination door rigging assemblies. It is another object of the invention to provide a versatile door for widespan openings capable of being mounted and rigged so that it can be operated from the interior or exterior of the building, as desired. It is another object of the invention to provide an improved building construction and more particuarly an improved airplane hangar having an easily openable wide span unitary panel construction door rigged for easy opening and closing by hand power.

Other objects of the invention include an improved the wide span door, each of the sections being supported individually supported theoretical sections set side by side and attached to form a unitary whole which constitutes the wide span door, each of the sections being supported by a stiffener along the vertical midline of the section, the door in its entirety being relatively flexible about vertical axes in the plane of the door, and to provide rigging supporting each stifr'ener and section attached thereto for moving the sections simultaneously along corresponding paths of motion and hence the whole door which they compose to the end that the entire unitary door shall be moved from closed to open position and vice versa. Another object of the invention is to provide a wide span door which in its vertical position has relatively great stiffness about a horizontal axis in the plane of the door but is relatively flexible about vertical axis in the plane of the door, together with provision for supporting the door at its upper and lower edges when in the closed position against wind pressure and other defiecting forces.

Other further objects of the invention include the provision of improved multiple latching apparatus for wide span overhead doors, together with improved operating mechanism for releasing the door from all of its latches simultaneously across its entire width. Other and further objects of the invention are those inherent in its apparatus herein illustrated, described, and claimed.

The invention is illustrated with reference to the drawings in which corresponding numerals refer to the same part and in which:

Figure 1 is a front elevational view of a portion of a building having a door opening closed by a door fabricated according to the present invention;

Figure 2 is a vertical sectional view taken along the line and in the direction of arrows 2-2 of Figure l, illustrating a section through the door when in closed position and illustrating the rigging by which it is supported and manipulated.

Figure 3 is a horizontal sectional view taken along the lines and in the direction of arrows 3-3 of Figure 2, illustrating the horizontal section through the door and the rigging by which it is supported and manipulated;

Figure 4 is a vertical sectional view taken along the lines and in the direction of arrows 4-4 of Figure 2, illustrating the rear side of the door in its closed position and the supporting and manipulating rigging;

Figure 5 is an enlarged horizontal sectional view taken along the line 5-5 of Figure 4, illustrating one of the points of t.e door at which the cable rigging is attached;

Figure 6 is an enlarged horizontal sectional view taken along the line and in the direction of arrows 6-6 of Figure 4, illustrating one of the door edges, and a fragmentary portion of one form of device for determining and stabilizing the path of movement of the door at the level of the cable hitch point;

Figure 7 is an enlarged vertical sectional view taken along the line and in the direction of arrows 7-7 of Figure 3, illustrating the manner of attachment of the adjustable cable guide pulleys of the cable to the counterbalance weight box frame;

Figure 8 is an enlarged vertical sectional view taken along the line and in the direction of arrows 8-8 of Figure 2, showing the cable attachment to the counterbalance weight box;

Figure 9 is an enlarged, fragmentary rear elevational view of the cable guide pulleys bracket over the door. This figure also shows a portion of the door supporting track and the manner of mounting the track;

Figure 10 is a fragmentary plan view taken along the line and in the direction of arrows 10-10 of Figure 9;

Figure 11 is an enlarged fragmentary vertical side elevational view of the cable guide pulley mounting bracket and pulleys together with a portion of the track frame and track mounting brackets, attached thereto, taken along the line and in the direction of arrows 11-11 of Figure 9;

Figure 12 is an enlarged fragmentary side elevational view through a portion of the building structure and the rear end of the door supporting tracks showing the manner in which the tracks are mounted;

Figure 13 is an enlarged fragmentary rear elevational view taken along the line and in the direction of arrow 13-13 of Figure 12;

Figure 14 is an enlarged fragmentary sectional view through the building framing taken in the direction of arrow 14-14 of Figure 12, showing the manner of attaching the upper end of the track supporting fixture to the building;

Figures 15, 16 and 17 as a group illustrate a somewhat modified form of construction for guiding the path of movement of the door panel at the level of the cable attachment thereto. Figure 17 is an enlarged view of a portion of the inside of the door near one edge and the adjacent building structure. Figure 16 is a sectional view through the door taken along the line and in the direction of arrow 16-16 of Figure 15, and Figure 17 is a horizontal sectional view through the door taken along the line and in the direction of arrows 17-17 of Figure 15.

Figures 18, 19, and 20 as a group illustrate the latching structure for holding the upper portion of the door in its closed position, together with the mechanism for releasing the latching apparatus so as to permit opening of the door. Figure 18 is a fragmentary, enlarged vertical sectional view through the door adjacent its upper edge and illustrates the bolts on the door and the cooperating latches mounted upon the adjacent structural frame-work of the building, together with a portion of the track supporting structure of the door. Figure 19 is a vertical, elevational view taken in the direction of arrows 19-19 of Figure 18. Figure 20 is a fragmentary vertical sectional view taken along the line and in the direction of arrows 20-20 of Figure 18.

Figure 21 is a schematic plan view illustrating an alternative location of the counterbalance weight box supporting frame;

Figure 22 is a horizontal plan view illustrating a further alternative positioning of the counterbalance weight box frame, where it is desired to provide for entirely exterior operation for the door supporting and operating mecha' msm.

Referring to the drawings, the front elevation of the door is illustrated in Figure 1 and as there shown, the door consists of a unitary flat panel having a width W and a heigth H for closing the door opening 0. As will be observed in Figure 2, the building B is provided with a roof R and the door opening is spanned, in the illustrated form of construction, by a structural steel truss T. The front surface of the structural steel truss T is closed by any suitable form of covering. In this instance a sheetv metal contact with the lower edge of the closure panel C. Suitable buffers may be provided against banging the door 10 against the lower edge of the panel C, during opening.

As will be observed in Figure 3, the door is constructed, in its preferred modification so as to utilize the entire span of the door opening 0. Thus as shown in Figure 3 the building B, which in this illustration is a T-plan aircraft hangar, is constructed'of walls, which may for example be of concrete building blocks. The wall included the front portions 11, which connects at the corner12 to an intermediate divider wall 13 which continues to the corner 14 and then extends along the longitudinal midsection of the building at 15 to the corner 16, thence continues along divider wall 17 to the corner 18 on the opposite outer wall of the building. An access door 19 is provided in the rear wall 20, of the hangar unit, where this wall is the opposite outer side wall of the building, or a suitable access door may be provided through the main door if desired, although this is not preferred since it reduces the strength of the main door. The outer wall 20 continues, and joins with a divider wall 21, (the corner not being illustrated in Figure 3), and the. divider wall then continues to the corner 22 and a wall runs along the longitudinal center line. of the building to the corner 24, and thence along a divider wall 25 to the corner 26 and if, as in this illustration, the building is a multiple unit hangar, will continue at 27 along the first side wall of the building. As will be seen from Figure 3, the building thus presents a door opening 0 having a width W0 and a height H from the floor F to the under edge ofthe panel C, as shown in Figure 2.

In the preferred form of the invention the entire width W0 of the door opening is available for utilization when the door is open, and is completely unobstructed by door jams or the like protuberances although these may be used as in Figures 15-17, is desired. In Figure 3, there is lightly illustrated a paved hangar floor FP, having a main central front portion on which the forward wheels of the airplane rest and a narrow portion extending into the rear of the hanger on which the tail wheel of the airplane may rest. The area of the'floor around the central paved floor FP may be filled with gravel or other lower cost material so as to be level with the panel and-provide dust free finish. Where the building is for the storage of implements, agriculatural machinery, construction machinery, or the like, the floor plan will, of course, be varied to suit the particular building needs, and the floor paved accordingly.

According to the present invention, the entire door of width W and height H is one unit, but may be considered theoretically as being composed of a plurality of panels set side to side and so composed as to form the unitary door structure. Thus referring to Figure 1, one panel may be considered as extending throughout the Width P1, from one corner 12 edge of the door to the dotted line 30. The next panel P2 extends from the line 30 to the line 31. The next panel P3 extends from the line 31 to the line 32. The next panel P4 extends, in the form illustrated, from the line 32 to the opposite corner edge '27 of the door. Each of the theoretical panels P1 through P4, or as many as may be considered as making up the door span is a self-supporting unit, all move together and are joined togetherto form a single unitary door. The door may be divided into any desired number of panels. For each of the panels P1-P4 or as many 6 as are used, there isa support provided along the vertical centerline of the panel. Thus for panel P1, support is provided along the center line CLl. Similarly, for the panel P2, support is' provided at its vertical center line (3L2, and similarly for the remaining panels. These centerline supports form the vertical backbone of each panel and may be any structural shape of appropriate stiffness, such as a pair of angles, as here shown. Since support is provided at the verticalIcenter line of each panel the transverse structural stiffness required for the support of each panel need only be sufficient to provide stiifness throughout the width of the panel, as, for example, throughout the dimension P1 for panel P1 rather than for the full width of the door. Structurally each panel is composed of a vertical backbone member providing sufficient stiffness against bending about an axis horizontally thru the panel as when the panel is loaded to (designed) wind loading from its exterior side. In the illustrated form, as shown in the figures in the drawings, this structural vertical backbone at the centerline of each panel is composed of two structural steel angles 34-34 set with flanges adjacent and with a slight spacing between them at 35 to allow for attachment of rigging. Then, across the width of each panel there extend a plurality of purlins, purlin 36 being at the lower edge.

Other purlins are set at intervals horizontally at spaced intervals up the floor height. Two such purlin stilfeners are provided at 37 and 38, at a horizontal level, part way up the door, which it is desired to guide along a predetermined calculated path, arcuate or straight, as hereafter explained. The purlins 36 through 41 extend all the way across the entire door, and accordingly make it into a structural whole, but they do not, and are not intended to provide stiffness across the entire door width; On the contrary purlins 36-41 need only provide su-fficient stilfness to prevent deflecting about the center lines CL1 etc., or stated another way, stiffness across the width P1 of a panel on the doors exterior surface. At the side edges of the door there are provided sheet metal channels as at 43, Figure 6, which finish the door edges and a similar channel may, if desired, be provided at 44, Figure 2, along the top edge of the door to provide a neat finish. The exterior surface of the door in this instance is provided with a standard form of sheet metal roof decking" 45, and this is attached to the purlins 36 through 41, by lead-headed nails 4646 or sheet metal screws or welding, as shown in Figures 5 and 6. Diagonal bracing is provided between the purlins and the sheet metal covering. Wood or other covering may be substituted for that shown at 45, but sheet metal is preferred. In the illustrated form the sheet metal covering 45 has a maximum stiffness about bending on an axis horizontally through the door. 2 vides stilfness in the same direction as is provided by the structural members 34-34 and the sheet metal 45 does therefore contribute considerably to the structural strength of the door against bending about a transverse axis in the plane of the door. The wind load against the panel P1 is taken first, by the sheeting 45, which bears on the purlins 36-41 and is then transferred to the structural members 34-34. When the door is closed (vertically), the structural members 34-34 are supported against deflection inwardly at the bottom by the sill S,

track which is fastened to the upper end to the structural V In other words, it pro- '7' members 34-44 forming the backbone of the panel. Thus referring to Figures 2, 3, 4 and 5 it is observed that a plate 48 is positioned between the structural members 34-34 of panel P1, the plate 48 being attached by bolts, welding or otherwise. Similar plates (or brackets) are provided at 118, 122, and 136 for panels P2, P3 and P4 respectively. The plate 48 (and also 118, 122 and 136) extends outwardly through the exterior sheeting of the door and each is provided with an eye through which a pin 4? passes for attaching the cable clevis, clevis 50 being provided for plate 48. The clevis 58 is the lower termination of the cable 51 of panel P1. As shown in these figures, and in Figure l, the cable 51, for panel P1, extends upwardly along the front surface of the door (in line with the structural members 34--34 which are behind the sheeting), and then passes over a pulley 52 which is arranged in a vertical plane and positioned so that the front part of its groove extends through a slot in the panel C above the door. The cable then passes around the pulley 52 and extends along a horizontal path directly inwardly into the building in a direction normal to the vertical plane of the door until it reaches the posi tion of guide pulley 54. The cable then passes around the pulley 54 by which it is guided and extends into the interior of the hangar space at a level above the upper surface of the door, and runs usually upwardly until it reaches the guide pulley 55 on the counterweight support frame 106. The cable then extends along a path 56 which (in this instance) is normal to the plane of the door and in this path of movement it is parallel to the similar course of travel of all of the other cables which are attached to and similarly support the remaining panels of the door, as will be explained hereinafter. It is important that at some place Within or without the building, all of the cables which support the panels, should run parallel to each other and then over a common drum.

The level at which bracket 48 is attached to the members 34-34 of the door is the same for each of the panels P1 through P4 (or as many panels as are used in making up the full width of the door). This level of brackets 48, 118, 122. and 136 (which is indicated in Figure 1 by line 140141) is horizontal and transverse across the door width and may be at any position from adjacent to the lower edge of the door to closely adjacent the middle of the door half way from top to bottom (which establishes the level of the cable clevis attach ments). I prefer that this level should be from 20% to 40% of the vertical height of the door, measured from its lower edge.

The upper end of each of the structural members 34-34 (of each panel P1-P4) is provided with a pivot hole and pin 56 to which there is pivotally attached the link 58 of a roller hanger 59, the latter being arranged to be supported by and travel in the track 60. In the illustrated form of the invention, the track is positioned immediately above the attachment bracket 48 (and similarly, tracks above each bracket 118, 122 and 136) so that both the bracket 48 and the center line of the track 60 are in a vertical plane normal to the door at the center line of the panel P1. Similar pulleys, brackets and track are provided for each of the other panels of which the door is composed.

I prefer to align the plane of lift of the cables 51, 116, 124 and 136 (see Figure l) with the corresponding tracks, but it must be understood that some misalignment may be tolerated. Also, if desired, a stiffener may be provided across the width of the door at the level of the brackets cable attachment clevis brackets 48, 1 18, 122 and 136, the stiffener being of sufficient strength to take the load between the structural members 34-34 of one panel and the similar structural members of the next adjacent panel. When this is done the brackets 48 etc. may be situated in any desired spacings and more brackets 48 (and cables) may beprovided than there are tracks provided for the same door. Stated another way, there need not be an identical number of cables along the front of the door and track supports at the top, but where an unequal number is provided, stilfness must also be provided in the door at the level of the clevis pin attachments (brackets 48 etc.) to allow for the non-symmetrical support of the panels constituting the full width of the door.

In the illustrated form, the tracks 60 are made to slant slightly upwardly within the building. This is preferred since the weight of the door will thereby produce a forward movement to latching position. Stated another way, the door tends to close at the top with greater ease when the tracks are. slanted. downward toward the door opening. In the form specifically illustrated the panels P1-P4 (or as many panels as. are used across the door), are similar andthe foregoing description of panel P1 will therefore suflice as a description of the construction. and support details of the remaining panels.

It should not however be assumed from the foregoing that the door is without any stiffness whatever in a transverse direction because the purlins 36-41 and the top channel 44 where used all contribute to the stiffness of the door against bending in about vertical axis through a plane of the door. All of the structural members 36-41 (and channel 44 where used) extend continuously from one edge of the door to the opposite edge of the door, thus forming through members upon which the exterior sheeting 45 may be attached. Likewise these members therefore providefor firm structural attachment of adjacent panels. The degree of stiffness thus provided would not be sufiicient to support the door if it were to be lifted only at the side edges at line '140-141 (Figure 1). The cables 51, 116 etc. provide a distributed lift which (acting as they do in unison) maintain the door flat.

In the construction of the door the exterior surfacing material 45, which is here illustrated as standard steel roof decking. is laid with the convolutions of the roof decking extending vertically. These roof decking sheets will seldom terminate at the lines 31, 31, or 32, which divide the door as a whole into the theoretical panels P1-P4. Hence, the exterior sheeting when nailed or otherwise fastened in place likewise ties the. entire door width together into a structural whole and contributes to the unity of construction provided by the strucural members 36 ,through 41 and 44.

At the level of the center line between the purlins 37 and 38, and at each opposite edge of the door, there are provided brackets as illustrated in Figures 4 and 6 for guiding the path of movement of that horizontal level of the door. Thus as shown in Figure 6 the bracket is composed of a pair of structural angles 58 and 59 which are bolted or otherwise attached to the inner flanges of the purlins 37, and 38. The angles 58 and 59 extend vertically and at the level of horizontal center line between the purlins 37 and 38 or closely adjacent thereto, there is provided a pivot pin .60 which is preferably welded to the angle 59 and passes through a hole in the angle 61. The pin 60 forms a pivot for tubular knuckle 61 which is welded to a radius rod 62. The radius rod extends upwardly and inwardly into the building and is fastened to a pivot 64 attached in this instance to the side wall of the building structure, or to such other struc tural support as may be available. In the building illustrated (which is a multiple nested T hangar building) the pivot 64 is a rod provided with suitable attachment and passes directly through the wall 13. A similar pivot 65 is provided at the opposite wall 25 and serves as a pivot point about which the radius rod 66 may swing arcuately. The radius rod extends down to the tube 67.

The two radius rods, 62 and 66, at opposite edges of the door, determine the path of movement of pivots 6160. The path of movement is accurate as shown by the dotted line 70, Figure 2, and accordingly as the door is opened it isforced outwardly as it moves up- 9. wardly and then drawsback to thedotted line position shown in Figure 10. At the same time the roller hangers 59 in each of the tracks 60 have traveled back to the dotted line position shown in Figure 2. Accordingly, when the door is opened the entire side wall of the building below the pivot 64 and 65 is totally unobstructed and available for the movement therethru of wide equipment such as an airplane. None of the span W of the opening is wasted by any protuberances such as door jambs.

The pulleys 52 and 54 for supporting the cable 51 of panel P1 (and the corresponding pulleys for the cables of the remaining panels) are supported on bracket structures as illustrated in Figures 9 and 11. As a practical proposition, the door truss spanning the opening when installed may have slight laterial misalignment and be curved and otherwise displaced slightly along its upper end chords. I have discovered that it is desirable, therefore, to provide support for the pulley rackets and tracks, which are carefully aligned, as these contribute to the easy operation of the door and make for neatness. At the same time I have discovered that it is desirable, in order to facilitate installation and adjustment to provide a unitary bracket for the support of the pulleys and also for supporting the front end of the track of each panel.

'This is accomplished by the structure shown in the Figures 9, 10 and 11.

Referring to these figures there is provided a bracket composed of a pair of arms 71 and 72, which are spaced apart and welded to a cross piece 74 at their rear ends. The two arms 71 and 72 are apertured' at their forward ends to receive a pin 75, provided with a grease fitting 76, which is held in place by the cotterpin 77. The pin 75 serves as a trunnion upon which the pulley 52 turns. I have discovered that high quality anti-friction bearings (ball or roller) should be used for all pulleys, in order to ease the operation of the door and this is a feature of the present invention. Upon the arm 72 there is also provided a stub 78 to which a nut, 79, is welded to allow the setscrew 80 to be turned therethrough. The setscrew 80 has a cup center and is located so that it will be slightly off center with respect to the vertical round pipe 81, to which the bracket is attached, when the bracket is in place on the pipe. Then by turning the setscrew 80 down against the pipe 81, the brackets may be attached to the pipe 81 and the pipe held in to the recess formed between the members 78, 74 and 72. Upon the member 74 there is an upstanding plate 82 which is accordingly in a vertical plane when the bracket is attached to the vertical pipe 80. The bracket is attached so that the plane of pulley 52 is vertical and is normal to the plane of the door 10, and the member 82, which constitutes a mounting plate, is accordingly parallel to the plane of the door and set inwardly slightly from the rear face of the door. Upon the plate 82 there is attached a supplementary bracket composed of a pair of parallel arms 84 and 85, see Figure 9, which are welded to a crosspiece 86, at the rear end and apertured at their forward ends to receive a pivot pin 88 similar to pivot pin 75. The pin 88 serves as a trunnion upon which the pulley 74 turns, pulley 54 likewise being provided with an anti-friction hearing, such as ball or roller bearings. The entire bracket 84-86 is a unit and is held in place by clamping plate 83 which is in turn held in place by a bolt 89 which passes through a hole in the plate 82 and into and is held by the nut 90 against the forward face of the plate 82. By loosening the bolt 89, the entire bracket 84-85 can be moved so as to bring the groove of pulley 54 nicely into alignment tangentially with the run of cable 51. The bracket 84-86 can be thought of as being pivoted about cable 51 as a center which accordingly causes the rear part of the bracket, which is clamped bythe plate 88, to slide or shift as required, during adjustment. The bolt 89 is much smaller than the space between the two arms 84 and 85, a wide latitude of motion is permitted for adjustment yet the entire bracket 84-86 can be clamped solidly in place once the adjustment is made. thus be placed in any plane horizontal 'to the floor or slanted upwardly as may be desired, so as to allow all of the cables running from the pulley 54 (and the corresponding pulleys of the other panels) to be aimed to their respective guide pulleys on the common bracket which supports the counter-balance weight.

The counterweight is hung on a sturdy frame, generally designated 100, which may be attached at various places within the building, or even at the exterior of the building. Thus it may be located as shown in Figure 3, or as shown in Figure 21 or 22. The frame must necessarily be in an elevated position so as to permit the counter-balance weight to move up and down underneath it. On the frame 100 there are provided pulleys 55 and pulleys 101, 102 and 104 which serve to guide all of the cables of the door to and along substantially parallel paths of movement. Thus cable 51, after passing around pulley 55 continues along the path 56 and the others are.

generally parallel to 56. Thus it will be observed, that the cables 51, 105, 106 and 107, after passing over their pulleys 55, 101, 102 and 104, respectively, move along paths of movement which are substantially parallel and substantially level and then pass over a common drum at 106 which is mounted in anti-friction bearings such as ball or roller bearings 108. The cables then pass downwardly to the weight box, to which they are attached. I prefer to make the cables 51 and a single piece, thus from the clevis 50, the cable 51 extends upwardly over the pulley 52 and thence after passing over pulley 54, cable 51 extends at an angle and it may extend upwardly depending upon the vertical elevation of the frame 100, to the pulley 55 and thence along the path of travel 56 to and thence downwardly around and down from the periphery of the drum 123. The cable then passes downwardly as shown at 109 in Figure 2 to an equalizer pulley 110, see Figure 8, which is pivoted on the shaft 111 of the counterweight generally designated 113. After passing around the pulley 110 (see Figure 8), the cable extends upwardly as at 111 in Figure 2 then around the drum 123 and forwardly along the path 112 which is substantially parallel to the path 56 of the corresponding run of the incoming cable. The cable then passes around the pulley 101 which guides the cable to pulley 114, from which the vcable then runs along a path substantially normal to the door to pulley 115 from which the cable then extends directly downwardly at 116 to the clevis hitch 117 of the plate 118 (similar to 48) which is attached to the structural framing of panel P2. I prefer to insert a turnbuckle 119 in the strand 51 and a turnbuckle may also be inserted in the strand 105 if desired although it is not strictly necessary. Accordingly, by running the cable 51 from the clevis 50 continuously as described to the weight box and then back to the clevis 118, around the pulley 110, there is a certain amount of equalization possible. At first blush, such equalization may be thought to be impossible, due to the fact that both of the cable strands at 56 and 112 run'parallel and at the same rate around the drum 123. However, when the door is all the way down in a closed position (and the weight box is up), rotation of the drum 123 may be forced slightly, which causes a slippage to occur between the cable and the drum 123. When this occurs equalization occurs at the pulley 110. A similar equalization occurs when the door is in an extremely elevated position. In this position I provide stop blocks as at 120-120 beneath the counterweight which is then in its lowermost position. As the counterweight rests upon the stop blocks .120, part of the weight is taken and further rotation of the drum 123 may then be forced because the cables tend to slacken slightly which therefore permits equalization at the pulley 110. V

.A similar method of rigging is provided for panels P3 The pulley 84 may.

and P4. Thus from clevis122 of panel P3 a cable strand extends upwardly at 124, passing over the vertical pulley 125 and the guide pulley 126 and thence along the path of travel 106 to guide pulley 102. Thence at 128 the strand passes along a course of travel parallel to the paths 56 and 112 of cables of panels P1 and P2. The strand then passes around the drum 123 and down and around, going down at 129 and around the pulley 130 which is likewise journaled on the shaft of the counterweight. The strand then passes upwardly and along a path 131 which is parallel to the strands 56 and 112, thence around the guide pulley 104 along the path 107 which is equipped with the turnbuckle 133, and around the guide pulley 134 and the vertical pulley 135, thence downwardly 136 as shown in Figure l to the clevis 137. The pivotal connection of all clevises, 50, 117, 122 and 127, are along the horizontal line 140--141, which as previously described is at a horizontal line position located at level between the lower edge of the door and about midway up the door, preferably at an elevation from to at the vertical height H of the door, measured from the lower edge.

Referring to Figure 8 the counterweight 113 is most conveniently made as a box composed of lumber, suitably nailed together. The box is reinforced by steel strapping at 138 and 139, the strapping being provided on opposite faces of the box and held together by through bolts. The steel strapping is apertured at the upper end and the shaft 111 passes through the straps which accordingly transfer the load directly to the bottom of the box. The pulleys and are spaced by pieces of pipe 140-140 and between the pulleys there is placed a hitch 141 having an eye at 142 by which the entire weight box may be lifted during the rigging of the door.

The shaft 111 transfers the lifting force down through the steel straps 111 which extend downwardly and outwardly and are fastened to the box at the bottom and also intermediate of the bottom and the top of the box. The box is filled with sand or gravel to a proper counterbalancing weight. Around the box there may be provided a structural shield at 142 which serves to prevent the user from getting under the weight box as it moves up and down. On the structure of the shield 142 there is mounted a bracket 143 upon which the shaft 144 is pivoted. The shaft of the bracket extends rearwardly of the structure 142 sufficiently so as to allow the crank 145 having handle 146 to be turned in its path of circular motion 147. It will be noted that by locating the crank as shown in Figures 2 and 3, that the crank occupies no more space than the thickness of the counterweight and therefore does not protrude into the interior of the building where it might be engaged by the tail of the airplane or other equipment in the building. A sprocket 148 is keyed to the shaft 144 and chain 149 runs from sprocket 148 to a similar sprocket 150 keyed to the shaft 151 upon which the common drum 123 is also firmly attached. By turning the crank 146 sufficient power may be imposed upon the door 107 to cause the uncounterbalanced weight of the door or box to be moved, thus permitting the door to be opened or closed.

The pulleys of the counterbalance weight support frame 100 and are mounted as shownron Figure 7. The frame 100 is composed of angles 152 and 154 welded to cross frame pieces 155155. The entire frame is attached by bolts and braces to the wall 17 and to the overhead structure of the building so that it is solidly mounted for taking the entire weight of the counter balance box 113. The frame is mounted so that the forward ends protrude sutliciently beyond wall 15 to provide space for mounting the plates 162, as shown on Figure 7, which serve as mountings for the bracket 163 forthe pulley 101. Similar brackets and mounting plates are provided for pulleys 55, .102 and 104. All of the plates 155 are parallel to the plane of the door (when closed) and accordingly the brackets 163 of pulley 101 and similar brackets of the corresponding pulleys may be shifted and movedv so as to bring the strands 56, 122, 108 and 131 into reasonable parallelism and to a level substantially equal to the top of the drum 123. Accordingly all of the strands run together and thence over the drum 123 whether for opening or closing the door. If desired, the strands 109 and 111, and the corresponding strands from the runs 106 and'107 may be clamped together above the pulleys 111 and 130 after equalization has taken place. Then if failure occurs in one of the individual strands 51, 105', or 107, it will not release its companion strand. Such attachment requires no more than a simple bulldog cable clamp around the strands 109 and its companion strand above the pulley 110 and a similar bull-dog cable clamp around the strand 129 and its companion strand above the pulley 130. These are loosened whenever equalization adjustment of the strands is desired and are then tightened again.

The mounting of the track 60 for panel P1 and the corresponding tracks for each of the remaining panels may most easily be accomplished by first welding the track to a structural support such as the length of structural T as shown in Figure 9 The T-section need not extend throughout the entire length of the track but only from adjacent to pulley bracket as shown in Figures 9-11, to beneath some structural member in the building overhead structure. The track can overhang to some extent at each end. Thus as shown in Figure 2 and in Figures 9 through 14, the track 60 is welded to a structural-T 165 which is apertured at its forward end to receive a bolt 166 which passes through a pendant 167 attached to the pulley bracket. The track 60 extends forwardly to the point 60A so as to allow the roller hangar 59 to move forwardly to whatever position is necessary to permit the door to come to its fully closed position. At the rear end of the structural-T 165 a similar aperture is provided at 168 through which the lower hooked end 169 of a support rod 170 is attached. The rod 170 extends upwardly and is bent so as to go over a purlin 171 which reaches across the rafters 172. In the illustrated building corrugated sheet steel roofing. is provided at A and the upper end of the rod 170 is bent at 170A so as to extend across the purlin through one of the corrugations in the roofing A where it is held against displacement. The exact position of the rod 170 may be varied and some lateral misalignment can be tolerated, since the rod and track will pull sideways as much as several inches when the door opens. Thus the rod 170 will swing enough so as to allow the track 60 properly to position itself relative to the various roller hangars 59 on the upper edge of the door. However, it is desirable that the rods 170 be placed as near as possible in the same vertical planes along the center lines of the structural members 34-34 of the panels.

When the door is first rigged, each of the pulley brackets which also supports the front end of the track 60 is adjusted vertically so that each of the tracks supports its fair share of the load of the door. Then the entire pulley bracket and track support structure as shown in Figures 9 and 10 may be solidly welded into the pipe 81 upon which they are mounted.

The latching arrangement by which the door 10 is held from vertical displacement inwardly at its upper edge, is shown in Figures 18 through 20. Along the inner angle forming lower chord of the truss there are provided a plurality of pivots 180, upon which the latches 181 are mounted. The latches are shaped so that their lower edges will ordinarily rest against the upper surface of the angle flange of the lower chord of the truss and thus keep them from falling downwardly to below the position. shown in full lines in Figure 18 and they are shaped so that they may rise as much as needed, as for example to the dotted line position shown in Figure 18, to permit the door bolts to move into latching position there beingone. bolt for each. latch. Along, the inner face of each of the structural members 34 across the width of the door there are likewise provided journals 182 in which a rod or pipe shaft 183 is mounted for limited rotation. The shaft 183 has attached to it handle 184 which is oridinarily held in a full line position as shown in Figure 18 by means of a spring 185, but handle 183 may be pulled downwardly by the rope 186 which has its lower edge attached to the door structure. The rope may be tied down at its lower end to limit upward movement of the handle or a stop may be provided on the handle in its up position. One bolt 188 is provided adjacent each pair of structural members 3434, Figure 4, and it is attached to the shaft 183 by a pair of spaced bearings 185185 which may be simple, short lengths of pipe welded co-axially and spaced from each other along the side of the pipe 183. A pivot pin 186 is loosely fitted in the pipe pivots 185 and a similar short length of pipe 187, which is welded to the lower end of the bolt 188, is held by the pivot pin. In the raised position the belt 188 extends upwardly between a guide at 189 to a position such that it will be received Within the notch 190 in the latches 181, and as the door swings home to the vertical and fully closed position, the upper edges of the bolt 188 causes its latch 181 to be lifted and the latches will then fall to the latching position when the door closes. It may be noted that the structural members 3434 extend upwardly beyond the lower truss member and members 3434 therefore stop again at the inner angle forming the lower chord of the truss. Thus as the door comes home to its closing position the bolts raise the latches 181 to the dotted line position and the latches fall with the upperend of the bolt received in the notch 190. There are four such bolts illustrated, one closely adjacent the center line of each of the panels P1-P4 of the doors shown. I prefer to use one bolt for each panel although more may be used if desired, and as previously stated the door may be composed of any desired number of panels, all forming an integral unity.

When it is desired to release the door it is only necessary to pull down on the rope 186 which causes the lever 184 to move arcuately in the direction of the arrow 191. This-causes all of the bolts to be drawn in unison to its dotted line position as shown in Figure 18, thus freeing the upper end of each bolt from the notch 190 of its latches 181. The downward pull on the rope 186 also is slightly inward in respect to the plane of the door and causes it to move slightly inwardly at the top due to the latch releasing pull. The operator then need only turn the crank 146 to elevate the door to its raised position.

In a practical embodiment of the door illustrated and described herein the total weight of the door amounts to approximately 1,650 pounds, and the counterbalance is about 1,300 pounds. The door can be operated with approximately 4 /2 turns of the drum 123 (6" diameter) by means of a 15" crank placed upon a shaft 151 or upon a shaft 144. This is sufiicient for opening or closing the door. The use of anti-friction ball bearings which is a feature of the preferred embodiment of my invention for all pulleys and for the mounting of drum 123 vastly decreases the amount of energy necessary for handling the door. Thus one man was able to operate the door through more than 200 opening and closing cycles in less than four hours time without being fatigued. The span of the door mentioned in this example is 39'4" and its height 10'2".

Where for structural reasons or for other necessary reasons it is desired to use a vertical track guide for determining the path of motion of line 140-'141 the door (Figure 1), this may be accomplished as shown in which is journaled upon the pin 203, the pin in turn passing through the-pressed steel channel 204 forming the edge of the door. The interior end of the pin 203 is supported on the lug 204 held by the angle 205 that is bolted to the purlin 37 and 38. Otherwise, the door structure is as previously described. When the door opens the pin 203 and roller 202 at each side of the door are accordingly permitted to move only within the confines of the track 200 along a straight line of motion which is accordingly communicated to the door, and the door is tipped as it is lifted to its fully opened position. 7

Referring to Figure 21, there is illustrated another and alternative location of the frame 200 upon which the main drum 107 for supporting the counter Weight is mounted. Such a location in the building may be preferred in some instances as where the airplane has a very wide horizontal stabilizer. The frame 200 is then slightly revised in plan so as to permit the pulleys 55, 101, 102 and 104 to be mounted for guiding the strands 51, 105, 106 and 107 along paths of movement parallel to each other and then to the drum 123 over which they pass to the counter balance weight box as previously described. Otherwise the construction is as previously described.

In Figure 22, pulleys are provided at 220, 221, 222 and 223 and are arranged above and generally parallel to the vertical position of the door so that the cable strands 51, 116, 124 and 136 may run directly upwardly to the pulleys. The pulleys may be arranged in closely spaced position laterally or at slightly differing elevations when viewed from the front of the hangar so that the strands 221, 222, 223 and 224 run parallel or nearly so yet closely adjacent to each other to the drum 123, then over the drum to the counterbalance weight. The form of rigging shown in Figure 22 accepts a certain amount of misalignment of the strand with the groove in the pulley as the door is elevated, particularly where the radius rod .type of guide as shown in Figures 2 and 3 is used for determining the path of movement of the lower section of the door. However, by making the pulley grooves of a fairly wide V-shape this mis-align ment will not be detrimental. The advantage of the rigging, shown in Figure 21 is that it permits operation of the door from the exterior of the building without need for a separate access door as shown in Figure 3, and additionally conserves interior building space. I

While doors of upwards of fifty foot span and heights of ten to fifteen feet can be manipulated manually by use of the improved constructions made possible by this invention, one may, if desired, use a motor power drive. Thus a reversible torque motor suitably geared down to approximately the same speed of rotation afforded by hand operations may be mechanically coupled to shaft 151 for driving it for opening and closing the door. A favorable speed of operation for shaft 151 (and drum 123) when operated by hand (drum 123 being 6.3" CD. and the door 10, 10 feet 2"x39 feet 4") is one turn of shaft 151 in from two to four seconds. The door in this example opens and closes favorably under those conditions. Slower operation is no disadvantage except a certain speed and firmness is useful in moving the door to final latched position; faster operation is unnecessary and produces jarring.

Closure of the edge of the door to the walls 8 (or 25) can be effected by fastening a flexible strip of weatherstop material such as sheet rubber or belting 225 along the edge of the door so that it nearly contacts the wall 8 as shown in Figure 6. The flexible weatherstop is held in place by a metal strip 228 which is, in turn, fastened by self tapping screws 227. Flexible weatherstop material such as felt strip, may likewise be provided along the front flange of channel 44 so as to contact the lower inner face of panel C, and a flexible apron applied to the lower edge of the door for closing it to the floor.

These latter have not been illustrated as they will conform to known practice, and in many instances may not be needed for the type of building under construction to which the doors hereof are fitted.

As many apparently widely different embodiments of this invention may be made without departing from the spirit and scope thereof is to be understood that I do not limit myself to the specific embodiments herein.

What I claim is:

1. In a building having a door opening in a wall thereof the top of said opening being defined by a structural member of the building, a door system comprising a flat unitary widespan door in the form of a panel which in its vertical position closes the opening, rigging for supporting the door including track means extending in a plane generally normal to the door opening and from closely adjacent the upper horizontal boundary of the door opening, roller hangers for movement along said track means, the upper edge of said door being suspended directly on said hangers, said rigging also including cables each extending from clevis hitch points located on the outside of the door along a common substantially horizontal clevis hitch point line transversely of the door at a level in the range of from substantially adjacent the lower edge of the door to a level substantially below the middle of the door, and thence upwardly outside the door and over guide pulleys, a common counterweight, connected to said cables, means connected to door system for simultaneously drawing in and letting out the cables for raising and lowering the counterweight, said rigging also including means at the sides of the door for guiding that part of the door at the approximate level of the hitch point location line along a predetermined up and down path of movement.

2. The apparatus of claim 1 further characterized in that the hitch point location line is at a level of from about to 40% of the vertical height of the door measured from the bottom edge.

3. The apparatus of claim 1 further characterized in that said means at the sides of the door for guiding comprises tracks supported vertically along the sides of the door and rollers attached to the door and rotatable on a transverse axis parallel to the plane of the door and located so as to run on said tracks.

4. The apparatus of claim 1 further characterized in that said means at the sides of the door for guiding comprises radius rods, one for each side of the door, each said radius rod being pivoted to the door and pivoted within the space of the building for swinging movement in a plane approximately normal to the door.

5. A widespan door system comprising a fiat, unitary rectangular door, track means extending approximately normal to the plane of the door when it is closed and in a common locating plane above the top edge of the door, roller hangers mounted in said track means for movement therealong the upper edge of the door being connected to the hangers for supporting part of the weight of the door and for translating the upper edge of the door rearwardly into the building and along said locating plane, a plurality of hitch points on the exterior face of the door, said hitch points being at a common substantially horizontal level in the range from substantially above the lower edge of the door to substantially below the middle of the door, a plurality of pulleys positioned above the door and above each hitch point, drum means mounted for rotation on a horizontal axis and at an elevated position, a counterweight of less than the Weight of the door below the drum means, cable means attached to each hitch point and extending upwardly, one over each pulley and thence along paths above the upper edge of the door and to and thence partially around said drum means and thence down and attached to said counterweight, and means at the side edges of said door for guiding that portion of the door at the approximate level of said hitch points along a predetermined patlllup and down 16 as the door is raised and lowered, means for mechanically rotating said drum means for taking in or letting out said cable means simultaneously for opening and closing said door.

6. The door specified in claim 5 further characterized in that a hand crank is mounted below the drum means so as to be operable by a person standing at ground level and is connected to the drum means for rotating it by hand power.

7. The door specified in claim 6 further characterized in that said drum means and hand crank are provided with a drive sprocket and are connected by a drive chain so as to be rotated simultaneously.

8. The door specified in claim 5 further characterized in that a protective shield is mounted around the path of movement of said counterweight and a hand crank is mounted on said shield so as to be rotatable by hand by a person standing at ground level, said hand crank being connected to the drum means for rotating it as the crank is rotated.

9. A widespan door for an opening in a building which opening is defined at the top by a building member extending across so as to define the top of said opening, said door comprising a flat unitary panel having top, bottom and side edges, track means extending into the space of the building and located in a common locating plane above the top edge of the door, roller-hangers mounted in said track means for movement therealong, means connecting the roller-hangers to the door adjacent its upper edge for supporting a part of the door weight and for translating the upper edge of the door rearwardly into the building and along said locating plane, a plurality of hitch points on the exterior face of the door, said hitch points being at a common substantially horizontal level in the range of positions from substantially above the lower edge of the door to substantially below a level halfway up the front of the door from the lower edge thereof, a plurality of primary pulleys mounted one above each hitch point and so as to be above the upper edge of the door, said primary pulleys being located so that a portion thereof extends outwardly beyond the front of the door when it is vertical, a drum mounted for rotation on a horizontal axis above the level of the door and remote from the door, a plurality of guide pulleys above the door mounted so as to define cable runs extending, one run from each primary pulley and thence to the drum, each cable run including a portion adjacent the drum where all cable runs are parallel to each other, a counterweight of a weight less than the weight of the door, positioned below the drum, a cable extending from each hitch point thence upwardly outside the door to and partially around the primary pulley which is above said hitch point and along one of the cable runs to and partially around said drum and thence downwardly and connected to said counterweight, means at the side edges of the door for guiding that portion of the door at the approximate level of the hitch points along a predetermined path up and down as the door is opened and closed, and means connected to the drum for rotating it for opening and closing the door.

10. The door specified in claim 1 further characterized in that a plurality of latch bolts are mounted along the upper edge of the door for engaging keepers positioned along the door opening, and means on the door is provided for manually moving said latch bolts simultane' ously for releasing them from their keepers.

ll. A widespan overhead door comprising a fiat structuralpanel for closing the door opening except for clearances at the edges when the panel is in an upright position, said panel having a plurality of upright stitfeners at spaced transverse intervals along the inner surface thereof, tracks extending in a plane generally normal to the upright plane of the door, said tracks extending from points above said stiffeners and thence rearwardly into the building, rolling supports attached to the upper end of each upright stiifener, said rolling supports being mounted on said tracks so as to roll along said tracks, said tracks providing support for the upper edge of said door panel, cable supports for each stiffener extending from an attachment on said stilfener' and thence vertically along the outside surface of the door panel to above the upper edge of the door panel, the attachments for each cable being along a horizontal axis slightly outside the outer surface of the door panel and at a vertical level ,between in the range from substantially above the bottom of the door and substantially below the middle of the door, cable drum means having a journal for rotatably mounting it having a weight less than the door weight, counterweight means, a plurality of guide pulleys for all of said cables for guiding said cables along parallel paths of travel, thence over said cable drum means and to said counterweight means, said cables being connected to said counterweight means, and drive means, and means connecting said drive means to the cable drum means for rotating the cable drum means for simultaneously moving all cables substantially equal increments for each increment of door opening or closing movement.

12. The overhead door rigging assembly of claim 11 further characterized in that said tracks comprises a pressed steel channel of rectangular cross-section supported by a structural element of inverted T-section to which the channel is attached at closely spaced intervals, and said structural element is supported from the bracket and structural member.

13. A door and rigging system comprising a flat unitary widespan door in the form of a panel which in its vertical position closes a door opening, rigging for supporting the door including rotatable drum means journalled for rotation on a horizontal axis at an elevation above said door, a counterweight below said drum means said counterweight being of a weight less than the weight of said door, track means extending in a plane generally normal to the door opening adjacent the upper horizontal boundary of the door, said track means extending into the building, roller-hangers mounted in each of said track means for movement therealong, means connecting each roller-hanger to the upper edge of the door for translating the top of the door back and forth, said rigging also including a plurality of cables, each extending from clevis hitch points located on the outside of the door, said clevis hitch points being at a common hitch point level which is substantially above the bottom of the door and substantially below the middle of the door, primary pulleys mounted above the door, one for each hitch point, each of said cables extending upwardly to and around its primary pulley and thence along a path of travel of said drum means, at least a portion of the runs of the cables to the drum means being parallel, said cables extending less than one turn around said drum means and thence downwardly to said counterweight, power means below said drum means and connected to the door and rigging system for operating the system to and from door open and door closed positions, and means connected to the sides of the door for guiding the sides of the door at approximately said common hitch point level up and down along a prescribed path of movement as the door is opened and closed.

14. The door system specified in claim 13 further characterized in that each of the cables, after passing around its primary pulley extends generally normal to the door when it is vertical and thence partially around a secondary guide pulley which is also substantially over the door and closely adjacent the primary pulley of said cable, the axis of said secondary pulley being in a plane substantially parallel to the door when the door is vertical.

15. The door system specified in claim 13 further characterized in that the counterweight is located at a position laterally removed from one side of the door.

References Cited in the file of this patent UNITED STATES PATENTS 102,379 Doe Apr. 26, 1870 600,707 Kohrisch Mar. 15, 1898 1,258,439 Ogden Mar. 5, 1918 1,274,443 Prescott Aug. 6, 1918 1,508,227 Jaray Sept. 9, 1924 2,023,193 Byrne Dec. 3, 1935 2,109,898 Byrne Mar. 1, 1938 2,331,497 Osborne Oct. 12, 1943 2,405,821 Ferris et al Aug. 13, 1946 2,595,794 Keller May 6, 1952 2,596,792 Robinson May 13, 1952 2,703,247 Wolf et a1. Mar. 1, 1955 2,751,624 Lipking June 26, 1956 2,804,953 Buehler Sept. 3, 1957 FOREIGN PATENTS 325,827 Italy Apr. 11, 1935 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No, 2,931,415 May 24 1960 Ralph L. Dugger It is herebir certified that error appears in the-printed specification of the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

Column 3, line 21 for "the wide span door each of the sections being supported" read wide span door structure composed of a plurality of column 4L line 71,, for "heigth", read height column 5 line 46,, for "is desired" read if desired line 50, for "hang r" read hangar column 9 line l4 for and" read through column 10 line l3 for "Figure" read Figures -3 column l3 line 5 for "oridinarily" read ordinarily column l7 line 14 Strikeout "counterweight meansQ" and insert the same after "it" in line 13 same column 17:.

(SEAL) Signed and sealed this 8th day of November 1960,

Attest: KARL H. AXLINE ROBERT C. WATSON Attesting Oflicer Commissioner of Patents 

